The
washing of hatching eggs is not recommended although many
producers think that visual cleanliness will increase their
chances of incubation success. It is more important to stress
providing good nesting facilities and frequent egg collection to
reduce egg contamination. Cleaning of eggs will then become
unnecessary.

The
reason that washing is harmful is that washing aide’s bacteria
to penetrate the egg shell through the small egg shell pores.
The egg has many natural defenses to prevent the bacteria from
moving through the shell. Washing removes the egg shell's
natural defenses against bacterial entry, and water provides an
environment that allows the organisms to literally swim through
the shell pores. When this occurs, the egg is overwhelmed by
more bacteria than it can destroy and egg contamination results.
Several washing aids and antibiotics have been tested to destroy
the bacteria but have not consistently improved egg
hatchability.

If
dirty eggs must be used for hatching, it is recommended that
they be incubated in an incubator separate from the clean eggs.
This will prevent contamination of clean eggs and chicks if the
dirty eggs explode and during hatching.